Networking Technologies

Chapter 1: Introducing Computer Networking

Objectives:

This chapter discusses networks in general and introduces several terms. The objectives important to this chapter are on page 1-1:

1. Understanding the term networking
2. Understanding the differences between centralized, distributed and collaborative computing.
3. Understanding the differences between local area networks, metropolitan area networks and wide area networks.
4. Understanding the three basic elements of networking.
5. Understanding the definitions of clients, servers, peers, transmission media and protocols.

Concepts:

Chapter 1 begins by defining networking as the sharing of information and resources. (page 1-2)

By this definition, centralized computing is not networking. Centralized computing is best represented by one large computer ( a mainframe) and one or more terminals. Terminals are not computers, only input/output devices.

Distributed computing may or may not be an example of networking. In this scenario, several "small" computers each carry out computing tasks. If they are linked together to share information and services, then it is networking.

Collaborative computing can only be done by networking. In this scenario, two or more computers share processing tasks, which they cannot do unless they are in a network. An example is the use of multiple computers to analyze radiotelescope data for the Search for Extra-Terrestrial Intelligence. The software to do so is currently available from the University of California at Berkeley. A more recent example is the Grid.org Research Program, which uses multiple computers for medical research.

Another model discussed is client-server networking. A client connects to and requests services from a server. The server responds to the client's requests. A similar model is the client-network model, in which the client connects to a set of services instead of a specific server.

Networks may be classified by the amount of area they cover. A Local Area Network (LAN) covers a small area, like a building or a campus. A Metropolitan Area Network (MAN) covers a city, linking computers at various locations. A Wide Area Network (WAN) covers an area larger than a MAN. This may be a network between cities or countries.

Very large WANs may be classified as Enterprise Networks, if they link LANs belonging to a single company. A Global Network is a large WAN that link LANs belonging to various entities (like the Internet).

A three part definition of a network is on page 1-8. A network must have:

1. At least two individuals with something to share. Things are shared with Network Services.
2. A method or pathway to connect them. Pathways are the Transmission Media.
3. Rules the individuals follow to communicate. Network communication rules are Protocols.

More terms follow in the chapter:

• Server - not just a computer, but the set of hardware and software used to provide a service.
• Client - any entity on the network that requests a service
• Peer - a network entity that may request and provide services simultaneously.

If entities on a network act as peers, then this is Peer-to-Peer Networking. If entities act in strictly defined roles, as either servers or clients, but not as peers, then this is Server-Centric Networking. Most PC networks are this type.

A point about the distinct roles of Transmission Media and Protocols is made: Transmission Media only provide a pathway to use for communication, a means of contact. Communication is not guaranteed until Protocols are followed, rules for the conversation.